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Abstract

Background

This study aimed to compare the levels of objectively-measured sedentary behavior
in children attending Montessori preschools with those attending traditional preschools.

Methods

The participants in this study were preschool children aged 4 years old who were enrolled
in Montessori and traditional preschools. The preschool children wore ActiGraph accelerometers.
Accelerometers were initialized using 15-second intervals and sedentary behavior was
defined as <200 counts/15-second. The accelerometry data were summarized into the
average minutes per hour spent in sedentary behavior during the in-school, the after-school,
and the total-day period. Mixed linear regression models were used to determine differences
in the average time spent in sedentary behavior between children attending traditional
and Montessori preschools, after adjusting for selected potential correlates of preschoolers’
sedentary behavior.

Conclusions

Levels of objectively-measured sedentary behavior were significantly lower among children
attending Montessori preschools compared to children attending traditional preschools.
Future research should examine the specific characteristics of Montessori preschools
that predict the lower levels of sedentary behavior among children attending these
preschools compared to children attending traditional preschools.

Keywords:

Sedentary behavior; Preschool; Montessori; Accelerometer

Background

The prevalence of childhood obesity in the U.S. has reached epidemic proportions in
recent decades [1,2]. Importantly, this trend also has been observed among preschool children [3,4]. There is growing recognition that time spent in sedentary behavior (i.e., sitting,
watching TV, and playing video games) is associated with an increased risk of childhood
obesity [5-8]. However, levels of sedentary behavior have not been described well, especially in
the preschool population, and the surveillance of sedentary behavior in preschool
children is needed.

Approximately 5.1 million children are enrolled in preschools or child care centers
in the U.S. [9], and the majority spend more than 6 hours per day in these settings [10]. It is important, therefore, to monitor levels of sedentary behavior in the preschool
setting. However, quantifying levels of sedentary behavior in young children is challenging
due to their intermittent movement patterns and inability to recall past behavior
[11].

Our research team has described preschoolers’ sedentary behavior levels during preschool
hours, using accelerometry and a direct observation system [12,13]. The majority of their time was spent in sedentary behavior during preschool hours
(42.1 min/hr or >80% of the observations). It was also observed that preschooler’s
sedentary behavior levels varied by school policies and characteristics [14,15]. However, those studies only included samples of children attending traditional preschools,
and to the best of our knowledge no study has described the levels of objectively-measured
sedentary behavior in children attending Montessori preschools, which have become
popular in recent years [16,17].

The popularity of Montessori preschools likely reflects their unique approach in terms
of children’s education. At least two-thirds of the preschool hours are devoted to
opportunities for self-chosen/directed activities, [18] and children attending Montessori preschools are allowed to freely move about during
the course of the day [19]. This likely provides more opportunities for ambulation compared to traditional preschools,
[20] and may reduce the time spent in sedentary behavior. Therefore, we suspected that
levels of sedentary behavior among children attending Montessori preschools might
differ from those of children attending traditional preschools. The purpose of this
study was to compare the levels of objectively-measured sedentary behavior in children
attending Montessori preschools with those of children attending traditional preschools.

Methods

Study design

A cross-sectional study design was used. Preschool children were recruited from traditional
and Montessori preschools in metropolitan Columbia, South Carolina. Trained data collectors
recorded arrival times and departure times from the schools every day in order to
distinguish in-school sedentary behavior from after-school sedentary behavior. Each
child’s daily sedentary behavior data were summarized by time of day: in-school, after-school,
and total-day.

Participants

The participants were preschool children aged 4 years old who were enrolled in 8 traditional
and 9 Montessori preschools. All traditional and Montessori preschools were identified
according to following criteria: 1) the school is licensed as a child care center
by the Department of Social Services, 2) the curriculum meets state standards, and
3) the teachers have degrees in early childhood education. Montessori preschools had
to meet following additional criteria to be invited in the current study: 1) the school
is accredited or a member of national Montessori associations and 2) the teachers
have a certification of Montessori teaching. The number of participants per preschool
ranged from 21 to 33 in traditional preschools, and from 19 to 62 in Montessori preschools.
Children with missing data for study variables were removed, and the following data
were available for analyses: in-school sedentary behavior (N=167 in traditional and
N=164 in Montessori), after-school sedentary behavior (N=137 in traditional and N=135
in Montessori), and total-day sedentary behavior (N=137 in traditional and N=136 in
Montessori). Written informed consent was obtained from children’s parents or guardians
prior to collection of data. The study was approved by the Institutional Review Board
at the University of South Carolina.

Accelerometer protocol

The preschool children wore ActiGraph accelerometers (ActiGraph model GT1M, Shalimar,
FL). The accelerometers were initialized to collect data in 15-second intervals (epochs)
to account for the spontaneous activity patterns of preschool children. The accelerometers
were attached to the child’s right hip (anterior to the iliac crest) using an elastic
belt. Each child was instructed to wear the accelerometer for five consecutive school
days (Monday – Friday), and their parents received information about how to wear and
remove the accelerometer during after-school hours. Trained staff checked each child’s
accelerometer at the beginning of each school day. If a child was not wearing the
accelerometer upon arrival at preschool, a temporary monitor was provided to collect
in-school sedentary behavior.

Sedentary behavior

Accelerometers collect and store count data according to movement frequency and intensity.
Cutpoints were applied to the count data to determine the time spent in sedentary
behavior. In the present study, a cutpoint of < 200 counts/15 seconds was used to
define sedentary behavior. This cutpoint was developed specifically for preschool
children (3 to 5 years) [21]. Using each child’s wear time as the divisor, cumulative time spent in sedentary
behavior was averaged on an hourly basis (min/hr). This was to take into account differences
in the monitoring times of children on a given day, and therefore allowed for comparisons
to be made across preschools. Sixty-minutes of consecutive zeros was considered as
non-wear time [22-24]. Due to variations in actual in-school hours among preschools, children have worn
the accelerometer for at least 50% of school hours to be included in the in-school
and total-day analysis. For the after-school and total-day analysis, children had
to wear the accelerometer for at least 4 hours during the after-school period. Days
that children were absent from preschool and days on which total wear time was ≥18 hours
(i.e., monitor malfunction) were excluded from the analysis because those days do
not represent typical days. It has been suggested that three or more days of accelerometry
monitoring provides reliable measures of accelerometry-derived sedentary behavior
in preschool children (intraclass correlations ≥ 0.80), [25] thus children who had at least 3 valid days of in-school and total day sedentary
behavior were included in the present study.

Demographic and anthropometric characteristics

Children’s age, gender, race/ethnicity, and socioeconomic status (SES) were reported
by a parent or guardian using a parent survey. Parent education level was measured
as a surrogate indicator of socioeconomic status. Child’s participation in after-school
sports program (i.e., number of times played per month) also was reported by a parent
or guardian. Child’s weight was measured to the nearest 0.1 kg using an electronic
scale, and height was measured to the nearest 1 mm using a stadiometer, after children
removed their shoes and outer clothing. Body Mass Index (BMI) was calculated (kg/m2) from the averages of height and weight.

Statistical analyses

Descriptive statistics (mean and SD; frequency and percent) for the participants were
calculated according to activity monitored during the different times of the day.
Independent sample t-tests and Chi-square tests were used to determine differences
in demographic and anthropometric variables between traditional and Montessori preschools.
The differences in time spent in sedentary behavior between children attending traditional
preschools and those attending Montessori preschools were determined using mixed linear
regression models that included age, gender, race, parent education level, BMI, accelerometer
wear time (hours/day), and preschool funding type (private or public) as covariates.
For after-school and total-day sedentary behavior, after-school sports participation
was additionally included as a covariate. Preschool was included as a random effect
in the mixed models to take into account correlations among children from the same
preschool. Mixed linear regression models also were used to determine if the covariates
influenced time spent in sedentary behavior. The following covariates were included
as independent variables: school type (Montessori or traditional), age, gender, race,
BMI, parent education level, preschool funding type, and child’s participation in
after-school sports program. The pseudo-R2 was calculated to determine the fraction
of variance explained by the model [26]. All data were analyzed using SAS version 9.2 (SAS Institute, Cary, NC, USA).

Results

Descriptive characteristics

Children attending Montessori preschools were predominantly white and more likely
to have parents with higher education levels, compared to children attending traditional
preschools (Table 1). Children attending Montessori preschools participated more frequently in organized
sports than those attending traditional preschools (Table 1). BMI was slightly lower among the children attending Montessori preschools, compared
to those attending traditional preschools. The average number of days and hours per
day that the children wore accelerometers during the in-school, after-school, and
total-day period were similar between children attending traditional preschool and
those attending Montessori preschools (Table 1).

Sedentary behavior between Montessori and traditional preschools

Overall, children attending Montessori preschools spent less time in sedentary behavior
than those attending traditional preschools during the in-school period, after adjusting
for age, gender, race, BMI, parent education level, preschool setting, and preschools
(Table 2). Also, children attending Montessori preschools spent less time in sedentary behavior
than those attending traditional preschools during the after-school and the total-day
period (Table 2). The lower time spent in sedentary behavior in Montessori preschools also remained
after further adjusting for child’s participation in after-school sports program (Table 2). Among all subgroups of children (gender, race/ethnicity, parental education level
or preschool funding type) those attending Montessori preschools engaged in less sedentary
behavior than those attending traditional preschools.

Multivariate analyses for the prediction of sedentary behavior

School type and gender were found to be significant predictors of in-school, after-school,
and total-day sedentary behavior (Table 3). Age and race were significant predictors of in-school sedentary behavior (Table 3). Parent education level was a significant predictor of total-day sedentary behavior,
and preschool funding type was a significant predictor of after-school sedentary behavior.
Total variances in sedentary behavior explained by the mixed model were 48%, 22%,
and 34% for in-school, after-school, and total-day, respectively (Table 3).

Table 3.Results of multivariate regression analysis for prediction of sedentary behavior in
preschool children

Discussion

This is the first study to describe and compare levels of objectively-measured sedentary
behavior between children attending Montessori and traditional preschools. We found
that the average time spent in sedentary behavior was significantly lower among children
attending Montessori preschools. Not only did these children spend less time in sedentary
behavior while in school, they also spent less time in sedentary behavior while out
of school. Our findings are of particular importance because they suggest that the
Montessori education system needs to be studied carefully to determine the specific
factors that facilitate lower time spent in sedentary behavior. In addition to the
finding that school type was a significant predictor of sedentary behavior, we also
observed that socio-demographic factors (age, gender, and parent education level),
and preschool funding type predicted time spent in sedentary behavior in multivariate
analysis. These findings suggest that socio-demographic characteristics and school-level
characteristics (e.g., policies and environments) have a significant influence on
preschoolers’ sedentary behavior. Both characteristics should be considered when developing
interventions that aim to reduce the time preschoolers’ spend in sedentary behavior.

There is evidence that preschool policies and practices can influence preschoolers’
sedentary behavior. Previous studies found that children attending preschools with
policies regarding sedentary opportunities (e.g., limiting time for prolonged sitting
and TV/DVD viewing) spent significantly less time in sedentary behavior compared to
those attending preschools without such policies [14,27]. The Montessori education system is based on a fundamental approach that encourages
children to teach themselves, with teachers serving as assistants in the classroom
[28]. Unlike traditional preschools, children in Montessori classrooms are not required
to sit and listen to teacher-directed instructions, but are encouraged to choose and
participate in individual or group activities [29]. This approach likely explains a proportion of variance in preschoolers’ sedentary
behavior. Traditional preschools could consider if it is feasible to include aspects
of this policy to reduce time spent in sedentary behavior.

Research also suggests that preschoolers’ sedentary behavior levels are affected by
the physical and social environment of the preschool. Children attending preschools
with environments that discourage sedentary behavior (e.g., fewer TVs and computers
or greater classroom size) have been shown to spend less time in sedentary behavior
while in school [15,27]. The Montessori preschool environments are based on the theory that “the best learning
is active” and that children learn within “prepared environments” in which they can
freely perform self-directed activities [29]. In general, the Montessori school classrooms are large and open-spaced to facilitate
children’s movement [29]. As an example, Montessori preschool classrooms typically are equipped with sets
of materials for light intensity physical activities (e.g., materials for sweeping,
dusting, cleaning, and gardening), and children are regularly engaged in physical
activities using those materials in school [28,29]. This could explain our observed difference in sedentary behavior during the in-school
period.

An interesting observation in this study was that children attending Montessori preschools
also spent less time in sedentary behavior out of school, compared to children attending
traditional preschools. This out-of-school sedentary behavior difference persisted
even after adjusting for child’s socioeconomic status and participation in after-school
sports program. This finding is of particular interest because it has been hypothesized
that children who are more sedentary (or active) during one part of the day would
compensate at other times of the day, resulting in daily total activity levels that
are constant [30]. Under the compensation hypothesis, environmental influences on children’s sedentary
behavior is limited, and biological control of sedentary behavior is predominant [31]. However, our data do not support this hypothesis, but rather suggest that school-based
interventions should be developed and implemented to reduce daily sedentary behavior
in preschool children.

It is also possible that the difference in after-school school sedentary behavior
could be due to a carry-over effect, whereby the Montessori school policies and environments
also influence children’s sedentary behavior out of school. In general, Montessori
preschoolers are encouraged to perform various types of light physical activity during
their attendance at school [32]. Such activities include serving snacks, washing the floor, dusting tables, watering
plants, and going outside to collect leaves [29,32]. Therefore, it is possible that children continue to perform these types of light
physical activities outside of school. In addition, parents who send their children
to Montessori schools are encouraged to limit the use of strollers and other carriers,
and the children of parents who follow this encouragement may spend less time in sedentary
behavior [32].

Alternatively, although we adjusted for numerous potential correlates of sedentary
behavior in preschool children (e.g., child’s socio-demographic factors, BMI, and
sports participation), [22,33,34] the observed difference in sedentary behavior out of school could be due to factors
such as neighborhood environments (e.g., hills in neighborhood and crime/safety),
[35,36] home environments and policy (e.g., number of TVs/computers, TV/computer in child’s
bedroom, and parent rules on screen time), [37-40] and parental behaviors (e.g., parent screen time) [33,41]. Future research is required to explore whether Montessori preschool policies continue
to reduce sedentary behavior after the child has left the school environment.

To our knowledge, only one previous intervention study has been designed to reduce
sedentary behavior in preschool children [42]. However, that intervention was designed to reduce TV viewing at home, and did not
intervene to reduce overall sedentary behavior in preschool children. In general,
opportunities to move freely in the traditional preschool classroom are limited. This
is likely due to early childhood educators being encouraged to employ formal curricula,
which focus primarily on cognitive and language-oriented academic achievement [43,44]. However, this approach may not be optimal for raising academic achievement [45-47]. Research suggests that children attending Montessori schools have higher test scores
in math and science compared to children attending traditional preschools [48,49]. Considering these data and our observations, it appears that the Montessori education
system can be a strategy to reduce sedentary behavior, while also allowing for high
academic achievement.

The current study had strengths and limitations that should be acknowledged. A major
strength of this study was the use of an objective measure of sedentary behavior.
Due to the poor recall ability and sporadic activity patterns of young children, assessing
the time spent in sedentary behavior in preschoolers is difficult. We quantified,
using accelerometers, the levels of sedentary behavior in preschool children across
the in-school, after-school, and total-day period. In addition, our samples of preschool
children were drawn from both private and public preschools. However, the generalizability
of our findings may be limited because participants of this study were volunteers
from preschools, and all participants were recruited from one geographic location
in the southeast U.S.

Conclusions

Results from this study showed that levels of sedentary behavior were significantly
lower among children attending Montessori preschools compared to children attending
traditional preschools. The lower levels of sedentary behavior were observed both
in and out of school. These findings imply that the policies and environments of the
Montessori preschool have the potential to influence the time preschoolers spend in
sedentary behavior. Future research should be conducted to identify the specific policies
and environmental factors of the Montessori preschool that discourage preschoolers’
sedentary behavior.

Abbreviations

SES: Socioeconomic status; BMI: Body mass index.

Competing interests

The authors declare no competing interests.

Authors’ contributions

WB contributed to the concept and design, drafting, revision, interpretation of the
data, and supervision. SNB and RRP contributed to the study hypotheses, refining the
data analyses, interpreting results, drafting the manuscript, and revising it through
multiple drafts. All authors have read and approved submission of the manuscript.

Acknowledgements

This study was supported by the National Institute of Health (Grant 5R01HD055451).
We thank all participants, parents, and preschools that participated in this investigation
and Drs. Jihong Liu and Michael W. Beets for editorial assistance in the preparation
of the manuscript.

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